Sensors Used in Instrumentation and Control

Ammeter - A meter to indicate electrical current. It is normally part of a DMM.

Bellows - This is a flexible volume that will expand or contract with a pressure change. This often looks like a cylinder with a large radius (typ. 2") but it is very thin (type 1/4"). It can be set up so that when pressure changes, the dis-placement of one side can be measured to determine pressure.

Bourdon tube- Widely used industrial gage to measure pressure and vacuum. It resembles a crescent moon. When the pressure inside changes the moon shape will tend to straighten out. By measuring the displacement of the tip the pressure can be measured.